1.6 Flashcards
1
Q
What is the enteric nervous system?
A
Autonomics + local plexi + interneurones
2
Q
What is the local plexi of the enteric nervous system of teh GIT divided into?
A
Meissner’s (submucosal) plexus –> mucosal secretions (parasympathetics increases mucosal secretions)
Auerbach’s (myenteric) plexus–> motility
3
Q
Where in the GIT microanatomy does the enteric system local plexi sit?
A
Meissner’s - sit in submucosa
Auerback’s - sits in muscularis propria between circular and longitudinal muscle
4
Q
From the lumen (deep) to superfical of the GIT name the layers + what they are divided into.
A
Mucosa
- Epithelium
- Lamina propria
- Muscularis mucosa
Submucosa
- contains Meissner’s plexus
Muscularis propria
- Circular muscle
- Auerback’s plexus
- Longitudinal muscle
Serosa or adventitia
5
Q
Smooth muscle in the GIT can be tonic-ally or phasic-ally contracted. Does parasym cause relaxation of contraction of these?
A
Tonic contraction relaxed by parasym (e.g. pyloric sphincter)
Phasic contraction contracts by parasym
6
Q
What is tonically contracted smooth muscle?
A
Muscle that is normally contracted (or most of the time)
Whereas phasic contraction smooth muscle is normally relaxed but will contract when gets a signal
7
Q
Function of peristalsis?
A
Movement of small boluses along GIT
8
Q
Function of segmentation?
A
Mixing food up without particularly moving food along any direction
9
Q
What is migrating motor complex?
A
Clearing undigested food when fasting
10
Q
What is mass peristalsis?
A
Colonic bulk movement
11
Q
Are salivary glands exocrine or endocrine glands?
A
Exocrine
12
Q
Type of secretions from parotid gland?
A
Mostly watery
13
Q
Type of secretions from submandibular gland?
A
Mixed mucous + watery
14
Q
Type of secretions from sublingual gland?
A
Mostly mucoid
15
Q
What do acinar cells of salivary glands secrete?
A
Amylase Lipase IgA Lactoferrin Lysozyme
16
Q
What do goblet cells of the salivary gland secrete?
A
Mucus
17
Q
The enteric nervous system is under the influence of which nervous system?
A
Autonomic
18
Q
Exocrine glands secrete primarily secretions from acinar cells, what do ductular cells do?
A
Secondary modification
19
Q
Does parasympathetic stimulation increase or decrease saliva production?
A
Increases
20
Q
Which muscles posteriorly border the abdominal cavity?
A
Psoas major
Quadratus lumborum
21
Q
Which muscles lie anterolaterally to the abdomen?
A
Transversus abdominus
Internal oblique
External oblique
22
Q
Which muscles lie anteriorly to the abdomen?
A
Rectus abdominus
23
Q
Blood supply to internal abdominal wall?
A
Epigastric arteries (they anastomose)
- Inferior epigastric comes off external iliac
- Superior epigastric is a continuation of internal thoracic artery (referred to as the internal mammary artery in the accompanying diagram)
24
Q
What is the peritoneum?
A
Single cell layer covering anterior abdominal wall + some viscera
25
What are retroperitoneal organs?
Only anterior aspect of organ covered by peritoneum
26
What is the mesentery?
Double layer of peritoneum which helps to connect an organ to another organ or structure
27
Where does the greater and lesser sacs lie?
Greater sac - cavity anterior to gastro-hepatic ligament
Lesser sac - cavity posterior to stomach
28
Which parts of the colon are retroperitoneal?
Ascending + descending
29
List all the intraperitoneal organs
stomach, spleen, liver, bulb of the duodenum, jejunum, ileum, transverse colon, and sigmoid colon.
30
List the retroperitoneal organs
Duodenum, the cecum and ascending colon, the descending colon, the pancreas, and the kidneys.
31
The whole GIT is derived from which embryonic cell type?
Endoderm
32
What is the foregut supplied by?
Coeliac trunk + pleuxs
33
What is the midgut supplied by?
Superior mesenteric artery + plexus
Drained by superior mesenteric vein
34
What is the hindgut supplied by?
Interior mesenteric artery and plexus
35
What is the cardia of the stomach?
Where the gastro-oesophageal sphincter lies
36
Largest part of the stomach?
Body
37
From superior to inferior name the parts of the stomach.
Fundus - top
Body
Antrum
Pylorus
38
Functions of the stomach
Store + mix food
Regulate release into intestine
Digestion + absorption of protein and vitamin B12
Immune defence - acid
39
What is the cephalo-gastric reflex indicated by?
What is it's role?
Thought/taste/smell of food
By vagal efferents result = inhibit stomach contraction
It allows stomach to expand without an increase in pressure for food storage during eating
40
What does the gastro-gastric reflex do?
When stomach distends --> inhibition of stomach contraction
It allows stomach to expand without an increase in pressure for food storage during eatin
41
What is gastro-oesophageal reflex?
Passive passage of gastric contents back up into oesophagus
Active would be vomiting
42
What is a physiological sphincter?
An area of increased tone E.g. gastro-oesophageal sphincter
Unlike the pyloric sphincter
43
What is GORD?
Gastro-oesophageal reflux disease
Can cause Barret's oesophagus (metaplasia) it is a pre-malignant condition which increases risk of oesophageal adenocarcinoma
44
List the cell types of gastric mucosa
```
Parietal cells
Chief cells
APUD cells
G cells
Mucus secreting cells
ECL cells
```
45
What do the parietal cells secrete?
Gastric acid + intrinsic factor (IF)
IF needed for B12 absorption
46
What do chief cells of the stomach produce?
Pepsinogen which becomes activated into pepsin and begins protein digestion
47
What do G-cells secrete?
Gastrin
48
What do ECL cells of stomach secrete?
Histamine
49
What do APUD cells in stomach secrete?
Somatostatin
50
What do PPIs tagert?
Parietal cells have H+/K+-ATPase proton pumps which are targeted.
Prevents H+ being pumped into the lumen
Parietal cells also have K+/Cl- pumps.
H + Cl = HCl
51
Why does vomiting cause metabolic alkalosis?
Stomach acid removed via vomiting. Parasym stimulation --> more acid
Stomach makes more HCl but in doing so makes bicarbonate which enters the blood + increases pH
52
How is stomach mucus produced?
Parasym stimulation --> ACh --> prostaglandins needed for mucus production
53
How do NSAIDs cause stomach ulcers?
They inhibit prostaglandin production which is needed for stomach mucus production.
But gastric acid is still being produced so not enough mucus to product lining of stomach form it's luminal acid
54
What does somatostatin (from D-cell) do to gastric acid production?
Somatostatin reduces acid by acting on ECl-cell so less histamine is released
Histamine increases gastric acid production
55
What is needed in the stomach to activate pepsinogen?
HCl
56
What do S-cell in the duodenum secrete?
Secretin
In response to intraluminal acid in duodenum
57
What is the role of secretin?
Secretin inhibits gastrin production and promotes somatostatin production to reduce HCl in stomach
Secretin protects duodenal cells from excess intraluminal acid
58
H. pylori is a bacterium that causes peptic ulcer disease. How is it able to survive the stomach acid?
Has the enzyme urease make alkaline coat via urea breakdown
Flagella to bury into mucus
Inhibits somatostatin production (which would normally inhibit histamine production and inhibits gastric acid production) = net increase in gastric acid
59
What is the plicae circulares of the small bowel microanatomy?
Folds in mucosa + submucosa
They are seen as transverse line on lumen of bowels in X-ray (important for differentiation of SI from LI on X-ray)
60
What are villae?
Folds of mucosa
They have microvilli
Crypts (named crypts of Leiberkuhn) lie at base of each villus
61
What makes up GALT?
Panneth cells - secrete lysozyme
Peyer's patches - secrete sIgA
62
Is the duodenum retro or intra peritoneal?
Retro apart from first part because it's connected to stomach (intraperitoneal structure)
63
Name the important structures that lie posterior to the 1st part of the duodenum
Portal vein
Gastroduodenal artery
Common bile duct
64
Which part of the duodenum lies anterior to right kidney and ureter?
2nd part - decending
65
Which part of the duodenum receives bile + pancreatic juice?
2nd
66
Which part of duodenum is longest?
3rd part (horizontal)
67
Why is the sphincter of Oddi special?
Divides embryological foregut from midgut
It is a muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater into the second part of the duodenum.
68
Which vessels pass anterior to the horizontal part of the duodenum?
Hepatic artery + portal vein
69
Where does the ascending (4th part) of duodenum terminate?
Ligament of Trietz
It's where the jejunum starts
70
Where are Brunner's glands found?
Duodenum only
The secrete alkaline fluid to neutralise gastric acid
71
What does the mesentery contain?
Neuromuscular supply
72
How do gastric parietal cells produce acid?
Using H+/K+-ATPase
73
What do statins inhibit?
HMG-CoA reductase which inhibits the 1st in the rate limit step of cholesterol synthesis
Leads to up-regulation of LDL receptors in the liver
Liver becomes better at removing LDL from circulation
74
Where is B12 absorbed?
Terminal ileum
Intrinsic factor-B12 complexes are needed for them to be taken up
IF made in stomach
75
Why can't dietary iron (Fe3+) be absorbed in it's current form?
Because only Fe2+ absorbed
So Fe3+ reduced to Fe2+ with ferric reductase and HCl
76
Is the pancreas retro or intra -peritoneal?
Retro
77
When does acute pancreatitis occur?
Activation of peptidases within pancreas (acinar cells) (usually trypsin)
They damage pancreas --> intrapancreatic inflammation --> extrapancreatic inflammation
78
Causes of acute pancreatitis
Mainly:
- Idiopathic 15%
- Gallstones 40%
- Ethanol 35%
```
ERCP (a procedure) 5%
Autoimmune
Scorpion bite
Mumps
Trauma
Steroids
Hyperlipidaemia
Hypothermia
Hypercalcaemia
Drugs
```
(I GET SMASHED pneumonia)
79
What is chronic pancreatitis usually caused by?
LT alcohol use
Exocrine insufficiency --> malabsorption --> steatorrhoea + low faecal elastase
Also present with recurrent abdo/back pain + weight loss
80
How are pancreatic enzymes secreted?
As inactive zymogens
81
Role of hepcidin?
Reduces total body iron stores
82
What is taeniea coli?
3 muscular bands that run longitudinally along bowel bowel
They are shorter than length of bowel so the bowel bunches up so it can fit along taeniea coli
83
What are haustrae?
Haustra of the colon are the small pouches caused by sacculation (sac formation), which give the colon its segmented appearance. The teniae coli run the length of the large intestine.
There is a wider distance between haustra than between the circular folds of the small intestine, and the haustra don't reach around the entire circumference of the intestine, in contrast to circular folds of the small intestine that do.
84
What are appendices epiploicae?
Epiploic appendices (appendices epiploicae) are small pouches of the peritoneum filled with fat and situated along the colon (on the outside of the large bowel), but are absent in the rectum.
85
Where is McBurney's point and why is it special?
3/4rds of the way from the umbilicus to the R anterior superior iliac spine
It's roughly where the appendix usually lies
86
When there is rectal distension (due to mass peristalsis) how does this information get transmitted?
S2-4 parasympathetic afferent
Parasymathpetic reflix
S2-4 efferents
Rectal contraction + internal sphincter relaxation
Voluntary control
External sphincter relaxation
87
Which lobe is more superior?
Caudate or Quadrate lobe?
Caudate
88
Which ducts come together to form the common bile duct?
Cystic duct from gallbladder
Common hepatic duct (from L + R hepatic ducts)
89
The acinus zones is split into 3 zones. Which zone has highest O2 supply and hence most affected by portal vein toxins?
Zone 1
90
Which zone in the liver deals with low O2 processes and suffers from hypoxic damage the most?
Zone 3
91
Which zone is most likely to be damaged due to build up of pressure in the hepatic vein (e.g. R heart failure)?
Zone 3
92
Which zone is most likely to be damaged in paracetamol OD?
Zone 1
93
What is the porta hepatis composed of?
Hepatic artery
Portal vein
Common hepatic duct
94
What is the dentate line?
Differentiation between endoderm and ectoderm
95
The inferior mesenteric vein + splenic vein + superior mesenteric vein joint to form?
Portal vein
96
Hepatocytes line what?
Sinusoids and form bile canaliculi
97
Functions of the liver
Protein synthesis (clotting proteins important!, plasma proteins)
Metabolism (blood glucose)
Bile (digestion + excretion of fats and fat soluble substances)
Immune funciton
Systemic interactions w/ CV + resp systems
98
What are bile acids?
Lipid derived, amphipathic weak acids conjugated with and aa (glycine/taurine usually)
99
Amphipathic means?
Have both hydrophilic and hydrophobic parts
100
What are bile salts?
Bile acids + Na+/K+
101
Where does bile go once synthesised?
Gallbladder for storage and concentration
102
What causes gallbladder contraction --> bile delivery to gut?
CCK
Cholecystokinin which present made in response to intraluminal fat in the SI
